This invention relates to a method and apparatus for making a matted continuum of continuously extruded filaments. More particularly, the invention relates to a method and apparatus for controlling the piled accumulation of filament to produce a matted continuum.
Open pore mats have been produced by a process which includes the extrusion of a multiplicity of molten thermoplastic polymer filaments over a short free-fall distance against a rotating cylinder at shallow contact angles. These filaments loop, pile and randomly lay into an accumulated continuum of a relatively uniform thickness that is bonded at the contact points of lap crossing to form a continuously developing mat on the rotating surface which is immediately quenched in a water bath.
Polymeric materials suitable for fabricating such piled mats include polyvinyl chloride, polypropylene, polyethylene, thermoplastic elastomers and other recyclable thermoplastic resins which are extrudable at elevated temperatures in the form of soft, flexible, continuous filaments and which at lower temperatures have the required stiffness, toughness and other physical and chemical characteristics to permit cohesion of the filaments.
Matting materials of this description have utility in such widely diverse applications as outdoor carpeting, underlayment for indoor and outdoor carpeting, soil retention matting and electrical cable splicing molds.
Other known processes for open pore mats of this type extrude the filaments onto a moving support and compress the filament bed in a nip.
The quench bath method is undesirable in several respects, particularly the fact that it requires an additional drying step. The compression method has an undesirable flattening effect on the filaments adjacent the surfaces of the filament bed.
It is, therefore, an object of the present invention to provide a process and apparatus for fabricating continuous filament polymer matting.
It is another object of the present invention to provide a process and apparatus for fabricating continuous filament polymer matting that requires no post-fabrication drying procedures.
Another object of the present invention is to provide a process and apparatus of the character described which enables improved control over the loft, or bulkiness of a continuous filament polymer mat.
A still further object of the present invention is to provide a process and apparatus of the character described for regulating the density, thickness and surface characteristics of a continuous filament polymer mat.